Well I use a silicone grease for lubricating my shafts. This is water proof, and doesn't attack the rubber.

I favour the Servisol brand- good quality and readily available in the UK- however I don't know if it's as easy to obtain that brand overseas.

However I use a stuffing box with my boat, so I don't actually FILL the tubes with grease- this a target modellers trick , that doesn't work at all well with submarines as you have water pressure to deal with.

Have a look here for some good modifications to your boats stern tubes-

I use the same grease on my U47 for the two gaskets and the stuffing boxes. it is a brand that i bought at my local bike shop, it is a silicone grease made for mountain bike hubs. claims to be "water repellant even if submerged". If you need a specific brand name, i will post again when I get out to the club house where I keep it.

hey guys go to your local hobby store and ask for prathers cable grease it is a silicone grease blue in color it comes in a 4 oz plastic jar and that one jar will last for several years I use a syringe to inject it in the tubes it is quite thick I have not had to grease the tubes more than once in 5 years like I said this stuff is really thick